Underwater well head encasement structure



April 26, 1966 v. c. JOHNSON 3,247,672

UNDERWATER WELL HEAD ENCASEMENT STRUCTURE Filed Aug. 29, 1962 2Sheets-Sheet 2 WVCE/VT C. riomvsou I INVENTOR.

United States Patent 247,672 UNDERWATER WE LL HEAD ENCASEMENT STRUCTUREVincent C. Johnson, 10377 Tennessee Ave, Los Angeles 64, Calif. FiledAug. 29, 1962, Ser. No. 220,217 1 Claim. (Cl. 6146) This inventionrelates generally to underwater protective structures and relates moreparticularly to underwater well head encasement structures.

Various problems have been encountered in underwater oilwell drillingand oil well completion installations, particularly in areas of moderateto heavy navigation, primarily because of the extreme vulnerability ofsuch installations to ships anchors and the possibility of deep draftcollision in the shallow water areas. Damage resulting therefrom couldlead to serious results, such as well blowouts, fire and pollution.Consequently such underwater oil well installations have been limited torelatively isolated areas.

Various methods have been used or proposed for underwater drilling andthe production of oil fromsuch operations, including the ocean floorcompletion technique. The latter method presents serious difliculti'es.For example, the network of submarine lines and well head equipmentgreatly restricts the use of the area as an anchorage for ships. Suchocean floor well installations that presently exist and the previouslyknown means for protecting these installations, include furtherdisadvantages. Typically, complex well head attachments are made atocean floor level and extend upwardly a minimum of approximately 12feet. Any such installations are therefore restricted to a water depthof sufficient overhead clearance to allow for passing ships. Harbors,bays and near shore areas are generally not of sufficient water depth tosafely permit oil well protrusions from the ocean floor.

Well head structures and the various means of encasement therefor now inexistence merely extend the protrusion above the ocean floor and offerlittle or no safeguard from damage by ships anchors. Lateral forces alsoare often found prohibitive to the complete enclosure of the encasementbeing used, and one type known to be presently used is an open bird cagetype encasement made of steel pipe materials. Obviously such anarrangement is vulnerable to ships anchors, even in isolated areas ofcomparatively deep water.

Further, such known types of protective structures are installed afterthe drilling and completing of the well which, of course, entailsdifliculties and problems, particularly in relatively deep water.

It is therefore an object of the present invention to provide protectivemeans which will overcome the above difiiculties and solve the problemspointed out above.

Another object of the invention is to provide a structure of thischaracter that is built in its enirety on land, with lifting lugs, etc.,that may be required for installation built in the completed assembly.

Still another object of the invention is to provide a structure orapparatus of this character constructed to meet the requirements for aselected well location and exposures related thereto.

A further object of the invention is to provide structure of thischaracter that is embedded in the ocean floor to such an extent thatonly a small portion is exposed above said floor, the portion exposedabove the ocean floor being determined by the depth of the water inwhich the installation is made.

A still further object of the invention is to provide an encasementstructure of this character which offers a deflective surface with noprotrusions that might capture and/ or hold a dragging anchor or thelike.

"ice

It is another object of the invention to provide an encasement structureof this character having a contour that is least affected by lateralforces of wave and current.

Still another object of the invention is to provide a structure of thischaracter that does not necessarily have to be water-tight andde-Watered, but whichvwill keep the interior free from foreign materialsand provide a deterrent to marine growth.

A further object of this invention is to provide an encasement structureof this character which, in the event of leakage from the well headstructure or structures, entrap the pollutant fluids and allow for earlydetection and corrective repairs.

Previous protective structures for underwater well heads haveaccommodated only a single well and it is another object of the presentinvention to provide an encasement structure which will accommodate aplurality of such well head structures.

A still further object of the invention .is to provide an encasementstructure of this character that is sturdy, effective and reliable inprotecting well head structures and the like from damage by shipsanchors, other equipment and/ or factors. I It is another object of theinvention to provide a structure of this character that is relativelyeasy to install.

It is still another object of the invention to provide an encasementstructure of this character that is relatively inexpensive tomanufacture.

The characteristics and advantages of the invention are furthersufiiciently referred to in connectionwith the following detaileddescription of the accompanying drawings, which represent certainembodiments. After Con sidering these examples skilled persons willunderstand that many variations may be made without departing from theprinciples disclosed, and I contemplate the employment of anystructures, arrangements, modes of operation or steps of the method thatare properly within the scope of the appended claim.

Referring to the drawings, which are for illustrative purposes only:

FIG. 1 is a diagrammatic view of equipment installing an underwater wellhead encasement structure showing said structure being lowered into ahole previously excavated therefor;

FIG. 2 is a similar view showing the encasement structure resting on thebottom of the excavation or hole;

FIG. 3 is a view of the structure installed and marked by a buoy;

FIG. 4 is an enlarged vertical section through the encasement structureshowing a well head structure therein; 4 F13. 5 is a sectional viewtaken on line 5-5 of FIG.

FIG. 6 is a fragmentary view of the structure showing an alternativearrangement.

The encasement structure is built in its entirety on land with liftinglugs and any other equipment that may be needed built into the structurewhich is constructed in accordance with the requirements of any specificinstallation.

Referring to FIG. 4, the structure is shown as being of precast concretewith steel reinforcements.

More particularly the encasement structure comprises a floor, indicatedgenerally at 10, the lower dome, indicated generally at 11, the lid,indicated generally at 12, and the manhole cover, indicated generally at14.

In constructing the encasement structure or cell, a ring of structuralsteel beams, indicated at 16, are assembled for the floor and a seriesof horizontal beams are also set in for the floor supports. Apredetermined number of pipe sections or conductor guides 17 are set ina pattern within the steel framework of the floor.

known mobile oil drilling platforms.

or barge hull 35 with legs 36 adjacent the ends.

Steel reinforcing bars 18 are also installed within the structural steelframework and lifting lugs 19 are installed at this time.

Forms for concrete are set up in the usual well known manner withspacers to allow the concrete to completely cover the steel frameworkfrom inside to the exterior. The concerete is then filled in, the Guniteprocess being one means that maybe used for this purpose. Thereafter theexterior surface is troweled to obtain the exact contour desired.

After the concrete has cured in the floor or principal structure, asteel framework, including the bar 20, is assembled and fitted.Concreting the dome follows the same procedure as the procedure followedin building the floor or principal structure.

The access cover 12 may be similarly formed as well as the manhole cover14.

The dome 11 has internal reinforcing ribs 21 which may be located alongthe steel reinforcing members 20. The upper end of the dome is notchedat the top to provide a horizontal shoulder 23 and a vertical shoulder24 for reception of the lower peripheral edge portion 25 of the accesscover, said portion 25 being so formed as to seat on the shoulder 23 andto be held against lateral displacement by the shoulder 24.

Adjacent the upper end of the access cover there is an opening 26 whichis surrounded by a peripheral or annular horizontal shoulder 27 from theouter edge of which there is an upstanding annular shoulder 28. Theperiphery of the manhole cover 14 is formed so as to extend into theopening 26 with a peripheral portion resting on the shoulder 27. Themanhole cover 14 is held against lateral displacement by the shoulder28.

The floor and dome 11 are secured together by any suitable means. Forexample, reinforcing rods or the like may be left extending upwardly atthe periphery of the floor so as to be embedded in the lower portion ofthe dome when constructed on said floor.

Means for raising and lowering or otherwise handling the floor and domeassembly comprise the lifting lugs 19. Lifting lugs 30 or other suitablemeans are provided for handling the access cover and there is a member31 for handling the manhole cover, member 31 being shown as an eye. Thelifting lugs 30 and the lifting lugs 19 may also be formed as eyes.

The first step of the installation procedure is to select the welllocation and then excavate a hole to rough dimensions. Various equipmentmay be used for making the excavation, such as clams, draglines, and/orjetting equipment operated from any suitable well known surfaceequipment. One type of such equipment is the George F. Ferris MarinePlatform, typical of well Such equipment is shown in FIGS. 1 and 2.

Referring to FIGS. 1 and 2, the equipment has a float There is also aderrick 37 which is movable longitudinally and laterally of the bargehull.

After selection of the well location the barge is towed to such locationand properly positioned. The legs 36 are then jacked down so that thelower ends rest on the ocean or underwater floor 38, where a continuedjacking raising of the hull 35 above the water barge'is towed beneaththe platform 35 and cables 41 of bridge cranes 42 aboard the platformare attached to the lifting lugs 19 of the concrete cell. It is to beunderstood that these lugs 19 are of sufiicient number and so arrangedthat the encasement structure will be held by the cables 41 in anupright manner so that the structure will not tilt.

After the cell or structure is lifted free the work barge is towed awayand the concrete cell is then lowered into the excavation, being heldsuspended in the exact position for final resting. While in thisposition fill material is placed and firmly compacted underneath thestructure and then around the perimeter thereof. In final position themain opening of the cell will'be a suitable predetermined distance abovethe fioor of the ocean. It has been found that having the main openingof the cell at approximately two feet above the ocean floor is asatisfactory arrangement, said main opening being the opening at the topof the dome.

Any suitable well known equipment may be used for compacting the fillmaterial, indicated at 45 and 46 underneath and around the cellrespectively.

With the encasement structure thus positioned and secured the accesscover islifted from the dome and set to one side. Any of the usualmethods of ocean drilling may then be followed, using either a fixedplatform of the type shown in FIGS. 1 and 2 or a floating platform.

It will be noted that the derrick 37 is moved toward one end of thebarge hull or platform when the encasement structure is being installedin the opening or hole 40. When drilling operations are conducted thederrick is moved to a position directly over the encasement structureand in alignment with the usual vertical opening, not shown, in suchbarge or platform.

The conductor guides in the bottom or floor of the encasement structureare funnel shaped with the large end at the top and serve as guide meansfor various tools and equipment during the drilling operations. Theseconductor guides are arranged in a suitable pattern but are so arrangedas to be in register with the main opening at the top of the dome sothat drilling equipment may be arranged in axial alignment with thevarious guides 17.

When drilling operations are conducted from a fixed platform a conductorpipe or the drill stem extends from the platform down into the oceanfloor, such conductor pipe being indicated at 48 in FIG. 2. Since thedrilling operations may also be from a floating platform or vessel asub-assembly is used at the underwater floor with exposed drill pipeextending from the vessel to the subassembly.

Alternatively, a floating vessel may be used and when used asub-assembly is provided at the ocean floor with the exposed drill pipeextending from the vessel to the sub-assembly. This method of drillingis also well known and need not be described.

After the well has been completed it is provided with the usual wellhead attachments which are disposed within the encasement structure,such completions following the usual practice.

The manifold 52 is provided within the encasement structure and attachedto the floor thereof by any suitable well known means. The manifoldstructure 52is used to gather the individual oil and gas lines, such asconduits 53, from each of the completed wells. There is an exit opening54 in the wall of the dome adjacent the manifold 52 for the main linesfor oil, gas and remote controls which are connected with the manifoldor enter therein. These main lines are disposed in a trench excavatedtherefor from the cell or encasement structure to a shore station, thetrench being deep enough so that these lines are buried to a depthsufficient for protection from ships anchors and the like.

After drilling and well completion operations are terminated, the accesscover is placed back in position on the dome, as shown in FIGS. 1, 3 and4, the manhole cover being in position on said access cover. Thereafterthe well heads are kept free of silt, sand and other foreign materialand will be protected from damage from anchors and the like. Forexample, anchors that may be dragging on the underwater floor would havenothing to engage and would merely pass over the smooth, rounded exposedportion of the encasement structure.

Consistent withother underwater well completion techniques, there is noparticular purpose served in de-watering the encasement chamber. Inother words, it is not necessary to maintain a dry chamber. However,with the small projection of the structure above the surface of theocean floor, the chamber will be kept free of any foreign materials andwill prove a deterrent to marine growth. It is to be noted that theaccess cover is joined to the dome and the manhole cover is joined tothe access cover so as to provide a reasonably tight fit to keep suchforeign materials out of the encasement structure and deter marinegrowth. If it is desired to provide a tighter fit between the parts,gaskets may be used.

Moreover, because of the tight connections between the access cover andthe dome and the manhole cover and the access cover pollutant fluidsresulting from leakage from the well head equipment in the structurewill be entrapped and allow for early detection and corrective repairs.

Referring to FIG. 6, there is shown an arrangement wherein there is adepending annular flange 60 carried by the bottom or floor of theencasement structure. This arrangement is used in the event theencasement structure is supported by piles 61 where the underwaterformation is too soft to permit the above described type ofinstallation. The upper end of the piles 61 will extend into the areadefined by the flange 60 and said flange will prevent the encasementstructure from being displaced from the supporting piles 61, said bottom10 resting on the upper ends of said piles.

In order to readily relocate any of the encasement structures a buoy 65is attached to the eye 31 of the manhole cover by means of a rope orother suitable element 66.

While the present encasement structure has been shown and described asbeing of reinforced concrete, -it may be of steel or other suitablematerial.

The invention and its attendant advantages will be understood from theforegoing description and it will be apparent that various changes maybe made in the form, construction and arrangement of the parts of theinvention without departing from the spirit and scope thereof orsacrificing its material advantages, the arrangements hereinbeforedescribed being merely for purposes of illustration.

I claim:

An underwater hollow oil well encasement structure, comprising:

' (A) a floor of concrete;

(B) annular structural steel elements embedded in the concrete,including an annular part adjacent the periphery of said floor;

(C) conductor guides set in a pattern in the floor, said 5 conductorguides extending through the floor and being funnel shape-d and havingthe larger diameter ends at the top;

(D) lifting lugs secured to the concrete floor at predeterminedperipherally spaced positions;

of said lower dome section;

(F) an access cover comprising a terminated spherical segment open atboth ends, the lower end of said access cover having an enlarged annularportion removably received in said recess at the upper end of the lowerdome section whereby the access cover is held in position on the lowerdome section;

(G) lifting lugs on the exterior of said access cover; (H) a shoulderabout the opening in the upper end of 5 the access cover;

(I) a manhole cover for the opening at the upper end of the accesscover, said manhole cover having its peripheral edge portion formed tothe shape of said opening and engageable with said shoulder whereby saidmanhole cover is removably maintained in position in said opening;

(I) and means on said manhole cover, engageable by lifting means, forremoval of said manhole cover.

References Cited by the Examiner UNITED STATES PATENTS CHARLES E.OCONNELL, Primary Examiner.

JACOB SHAPIRO, JACOB L. NACKEN'OFF, EARL I.

WITMER, Examiners.

(E) a dome comprising a lower terminated dome section secured to theconcrete floor and having an access opening at the upper end, said lowerdome section being of reinforced concrete with the larger diameter endattached to said floor, there being a groove about the access opening atthe upper end

